improvement in and relating to power tools

Abstract

To reduce the amount of time required to remove and replace a cover plate or cap ( 42 ) in an aperture in power tool housing, a cap assembly ( 32, 34, 38,42 ) for coupling to a housing of a power tool is proposed, which aperture facilitates location of a drum within, and removal of the drum from, the housing, the cap assembly ( 32, 34, 36, 38,42 ) also being for receiving an end of drive shaft of the tool adapted to drive and rotate the drum relative for the tool housing to remove material from a surface of a workpiece, the cap assembly ( 32, 34,38,42 ) comprising: a combined clamping ( 32, 34, 36, 38, 42 ) and shaft aliggnment with the shaft ena and a clamping position in engagement with the shaft end. To permit both planing and sanding to br performed using a single drum a drum ( 16 ) comprising an at least one mounting channel ( 56 ) for receiving an at least one planer blade ( 96 ) and the drum being adapted ( 120 ) to receive a tubolar sanding element ( 114 ), is proposed. To provide efficient extraction of material re-moved by a power tool, a tool housing ( 14 a ) having a primary chamber ( 130 ) in the housing,a secondary chamber ( 132 ) in the housing and an impeller ( 138 ) for generating a negative pressure differential between the primary chamber ( 130 ) and the secondary chamber ( 132 ) is proposed.

1 . A power tool comprising:
 a tool housing;   a drum adapted for removing material from a surface of a workpiece, the drum adapted to be releasably mounted within the housing;   a drive shaft adapted to drive and rotate the drum relative to the housing, for removing material from the workpiece surface;   an aperture in the tool housing for facilitating location of the drum within, and removal of the drum from, the housing; and   a cap assembly for coupling to the tool housing to close the aperture, the cap assembly adapted to receive an end of the drive shaft to facilitate mounting of the drum within the housing;   wherein the cap assembly comprises a combined clamping and shaft alignment mechanism which is movable between a release position out of engagement with the shaft end and a clamping position in engagement with the shaft end, and wherein the mechanism is arranged to automatically align the shaft and thus the drum on an optimal rotation axis during movement towards the clamping position and further comprising a first clamping member adapted to abut an outer surface of a wall of the housing and a second clamping member adapted to abut an inner surface of the wall of the housing, wherein the mechanism comprises a threaded securing member which, when rotated, draws the first and second clamp members together to clamp the housing wall and wherein the securing member is adapted to receive the shaft end and comprises or carries a bearing within which the shaft end is received, to facilitate rotation of the shaft relative to the/a main part of the securing member.   
     
     
         2 . A power tool according to  claim 1 , wherein the second clamping member comprises a nut threadably coupled to the threaded securing member and which advances or retracts along the securing member when rotated. 
     
     
         3 . A power tool according to  claim 2 , wherein the second clamping member further comprises a plate defining an abutment surface for abutting the housing wall, which plate may be adapted to engage in a slot formed in the housing wall. 
     
     
         4 . A power tool according to  claim 1 , wherein one of the cap assembly and the housing defines an at least one alignment member. 
     
     
         5 . A power tool according to  claim 4 , wherein the at least one alignment member is a rib. 
     
     
         6 . A power tool according to  claim 5 , wherein the other one of the cap assembly and the housing defines a corresponding at least one alignment recess. 
     
     
         7 . A power tool according to  claim 6 , wherein engagement between the alignment member and the recess facilitates alignment of the shaft and drum on the optimal rotation axis. 
     
     
         8 . A power tool according to  claim 6 , wherein the cap assembly comprises a cap shaped to cover the aperture. 
     
     
         9 . A power tool according to  claim 8 ,  6 , wherein the cap defines one of the alignment member and the recess. 
     
     
         10 . A power tool according to  claim 9 , wherein the other one of the alignment member and the recess is defined by a wall of the housing. 
     
     
         11 . A power tool according to  claim 9 , wherein at least one surface of the alignment member and at least one surface of the recess is inclined. 
     
     
         12 . A power tool according to  claim 1 , wherein a secondary aperture is formed in the housing and the cap assembly further comprises a cap portion adapted to close the secondary aperture. 
     
     
         13 . A power tool according to  claim 12 , wherein the tool further comprises a dust extraction chamber and the secondary aperture opens on to said dust extraction chamber of the tool. 
     
     
         14 . A power tool according to  claim 1 , wherein the drum is located such that a main axis of the drum is perpendicular to a main axis of the tool. 
     
     
         15 . A power tool according to  claim 1 , wherein the aperture is formed in a side wall of the housing. 
     
     
         16 . (canceled) 
     
     
         17 . A cap assembly for coupling to a housing of a power tool to close an aperture of the tool which aperture facilitates location of a drum within, and removal of the drum from, the housing, the cap assembly also being for receiving an end of a drive shaft of the tool adapted to drive and rotate the drum relative to the tool housing to remove material from a surface of a workpiece, the cap assembly comprising:
 a combined clamping and shaft alignment mechanism which is movable between a release position out of engagement with the shaft end and a clamping position in engagement with the shaft end, the mechanism arranged to automatically align the shaft and thus the drum on an optimal rotation axis during movement towards the clamping position and further comprising a first clamping member adapted to abut an outer surface of a wall of the housing and a second clamping member adapted to abut an inner surface of the wall of the housing, wherein the mechanism comprises a threaded securing member which, when rotated, draws the first and second clamp members together to clamp the housing wall and wherein the securing member is adapted to receive the shaft end and comprises or carries a bearing within which the shaft end receivable, to facilitate rotation of the shaft relative to the/a main part of the securing member.   
     
     
         18 . (canceled) 
     
     
         19 . A power tool for removing material from a surface of a workpiece, the tool comprising:
 a tool housing; and   a drum adapted for rotation relative to the housing, the drum comprising an at least one mounting channel for receiving an at least one planer blade to remove material from the workpiece surface in a planing action when the drum is rotated, and the drum being adapted to receive a tubular sanding element which element is located around the drum and which defines a sanding surface for abrading the workpiece surface when the drum is rotated;   wherein, in use, the tool is adapted to be configured for a planing operation by mounting an at least one planer blade in the at least one mounting channel and to be configured for a sanding operation by mounting of a tubular sanding element around the drum.   
     
     
         20 . A power tool according to  claim 19 , wherein the drum is permanently fixed in position. 
     
     
         21 . A power tool according to  claim 19 , wherein the drum comprises a plurality of channels, each channel adapted to receive a respective at least one planer blade. 
     
     
         22 . A power tool according to  claim 19 , wherein the drum is dimensioned to be a close-fit with the tubular sanding element for driving and rotating the element. 
     
     
         23 . A power tool according to  claim 19 , wherein the drum defines an abutment surface for abutment with the tubular sanding element in a friction fit, for driving and rotating the element. 
     
     
         24 . A power tool according to  claim 19 , wherein one of the drum and the tubular sanding element define a drive protrusion. 
     
     
         25 . A power tool according to  claim 24 , wherein the other one of the drum and the tubular sanding element defines a corresponding drive recess to receive the drive protrusion. 
     
     
         26 . A power tool according to  claim 25 , wherein a plurality of drive protrusions and corresponding recesses are provided. 
     
     
         27 . A power tool according to  claim 19 , wherein the tool comprises an at least one blade cartridge adapted to be releasably mounted in the drum recess. 
     
     
         28 . A power tool according to  claim 27 , wherein the blade cartridge comprises a mounting member adapted to be located in the drum channel, an at least one planer blade and a clamping member for clamping the blade to the mounting member. 
     
     
         29 . A power tool according to  claim 28 , wherein the clamping member is configured to exert a clamping force on the blade to clamp the blade to the mounting member. 
     
     
         30 . A power tool according to  claim 28 , wherein the mounting member and the clamping member define respective apertures which apertures align when the clamping member is coupled to the mounting member and the cartridge located in the drum channel. 
     
     
         31 . A power tool according to  claim 30 , wherein the aligned apertures are shaped to receive a locking element for locking the cartridge to the drum. 
     
     
         32 . A power tool according to  claim 28 , wherein the mounting member defines a blade mounting surface shaped to receive the blade, and further comprises a locating protrusion shaped to engage a corresponding locating recess in the blade. 
     
     
         33 . A power tool according to  claim 32 , wherein the clamping member comprises a clamping surface adapted to abut the blade to clamp the blade against the mounting surface of the mounting member. 
     
     
         34 . A power tool according to  claim 33 , wherein the clamping member comprises a protrusion defining a pivot point about which the clamping member pivots when the cartridge is secured to the drum, to exert a compressive clamping load on the blade. 
     
     
         35 . A power tool according to  claim 19 , wherein the tool comprises a drive shaft for driving and rotating the drum. 
     
     
         36 . A power tool according to  claim 35 , wherein the tool further comprises a mounting assembly for mounting the drum on the drive shaft. 
     
     
         37 . A power tool according to  claim 36 , wherein the mounting assembly comprises first and second locating elements. 
     
     
         38 . A power tool according to  claim 37 , wherein the first and second locating elements are adapted to engage respective first and second ends of the drum and to be mounted on the drive shaft for thereby locating the drum on the shaft. 
     
     
         39 . A power tool according to  claim 36 , wherein the mounting assembly further comprises a threaded locking nut adapted to engage a threaded portion of the drive shaft for securing the drum to the shaft. 
     
     
         40 . A power tool according to  claim 38 , wherein the locating elements are dimensioned to be a close-fit on the shaft so as to locate the drum as accurately as possible. 
     
     
         41 . A power tool according to  claim 40 , wherein the locating elements are adapted to engage the tubular sanding element. 
     
     
         42 . A power tool according to  claim 41 , wherein the locating elements comprise abutment surfaces which are inclined relative to an axis of the drum for engaging corresponding surfaces on the tubular sanding element. 
     
     
         43 . (canceled) 
     
     
         44 . A combination planer and sander assembly for a power tool, the assembly comprising:
 at least one planer blade;   a tubular sanding element defining a sanding surface;   a drum having an at least one mounting channel for receiving the at least one planer blade;   wherein the drum is adapted to receive the tubular sanding element, the element located around the drum;   and wherein, in use, the drum is adapted to be configured for a planing operation by mounting of the at least one planer blade in the at least one mounting channel and to be configured for a sanding operation by mounting of the tubular sanding element around the drum.   
     
     
         45 . (canceled) 
     
     
         46 . A power tool comprising:
 a tool housing;   a primary chamber in the housing for receiving a drum adapted for removing material from a surface of a workpiece;   a secondary chamber in the housing;   a radial flow impeller for generating a negative pressure differential between the primary chamber and the secondary chamber, for encouraging material removed from the workpiece surface by the drum to pass from the primary chamber and into the secondary chamber; and   an opening formed in a wall of the housing provided between the primary and secondary chamber and through which opening removed material passes into the secondary chamber;   wherein the opening extends in a direction along a length of the drum, and wherein the dimension of the opening in the length direction of the drum is at least equal to a length of an operative surface of the drum.   
     
     
         47 . A power tool according to  claim 46 , wherein the power tool is a power planer, a power sander or a combination power planer and sander. 
     
     
         48 . A power tool according to  claim 46 , wherein the opening is elongate and arranged on a tangent of the drum. 
     
     
         49 . A power tool according to  claim 46 , wherein the secondary chamber comprises an outlet for passage of removed material from the chamber, and the impeller is arranged to direct material through the outlet. 
     
     
         50 . A power tool according to  claim 49 , wherein the radial flow impeller is located in a flow path extending from the drum, through the opening into the secondary chamber, and from the secondary chamber into and through the outlet. 
     
     
         51 . A power tool according to  claim 49 , wherein the radial flow impeller is located in a portion of the secondary chamber which is isolated from a flow path extending from the drum, through the opening and into the secondary chamber, and from the secondary chamber into and through the outlet. 
     
     
         52 . A power tool according to  claim 50 , wherein the radial flow impeller is arranged to direct a jet or stream of air past the opening and into the outlet, to draw the removed material from the primary chamber through the opening. 
     
     
         53 . A power tool according to  claim 46 , wherein the radial flow impeller comprises a plurality of impeller blades. 
     
     
         54 . A power tool according to  claim 53 , wherein the radial flow impeller further comprises two sets of impeller blades, the sets provided on opposite sides of the impeller. 
     
     
         55 . (canceled) 
     
     
         56 . (canceled) 
     
     
         57 . A power tool according to  claim 46 , wherein the operative surface of the drum is a portion of a surface of the drum adapted to actively facilitate removal of material from the workpiece surface. 
     
     
         58 . (canceled) 
     
     
         59 . (canceled) 
     
     
         60 . A power tool according to  claim 57 , wherein the operative surface of the drum is that portion of the drum surface which carries or supports a planer blade or sanding surface, and/or the effective area of the drum over which a material removal activity occurs. 
     
     
         61 . (canceled) 
     
     
         62 . (canceled) 
     
     
         63 . (canceled) 
     
     
         64 . (canceled) 
     
     
         65 . A power tool according to  claim 74 , wherein the drum segments are adapted to be located on a drive shaft and to be locked in position by a locking member, whereupon the compressible member is compressed and expanded radially to abut the sanding element or the like. 
     
     
         66 . A power tool according to  claim 72 , wherein the drum comprises three drum segments with compressible members located between the adjacent segments. 
     
     
         67 . A power tool according to  claim 71 , wherein the drum segments together define one of a keyway and a key, for engaging with a corresponding key or keyway on a drive shaft for driving and rotating the drum. 
     
     
         68 . (canceled) 
     
     
         69 . A power tool according to  claim 54 , wherein the radial flow impeller is a fan or a propeller. 
     
     
         70 . A power tool according to  claim 46 , wherein the tool comprises a plurality of radial flow impellers. 
     
     
         71 . A power tool according to  claim 46 , wherein the drum comprises a plurality of drum segments which together form the drum. 
     
     
         72 . A power tool according to  claim 71 , wherein each segment is generally cylindrical and comprises a compressible member. 
     
     
         73 . A power tool according to  claim 72 , wherein the compressible member is an elastomeric O-ring, located between adjacent segments, for abutting a material removing element. 
     
     
         74 . A power tool according to  claim 73 , wherein the material removing element is a tubular sanding element.